Back in 1809, with a quick replay of where we left off at the end of Act 1 – a pistol shot at dawn.
Jellaby comes into the room, and lets in Septimus from outdoors.
Septimus has brought a dead rabbit he apparently shot himself, for one of Thomasina's favorite dishes: rabbit pie.
Exposition time! Septimus spent last night in the boathouse, and the house is much emptier than it was the day before: Captain Brice left with the Chaters during the night, and Lord Byron departed during the wee hours as well.
Jellaby says that Lady Croom looked for Septimus in his room overnight, but didn't find him there.
Septimus asks if Byron remembered to leave his copy of The Couch of Eros, but Jellaby says that Byron didn't leave anything behind, not even a tip for the butler.
Septimus remedies this, and the cash loosens Jellaby's tongue. The 411: while Mr. Chater and Captain Brice got drunk together, Lady Croom ran into Mrs. Chater at the door of Lord Byron's room, and neither was especially pleased to see the other, to say the least.
At this point Lady Croom enters, cutting the gossip train short.
Lady Croom sends Jellaby out to get her tea, and confronts Septimus about two letters she found in his room: one to herself (about sexy things), one to Thomasina (about rice pudding), both marked to be read only after Septimus's death.
Lady Croom says that she's banished Byron, Brice, and the Chaters for their sins, and expects Septimus to follow them shortly.
Lady Croom recounts her own version of the previous night's events, with a few edits (in her telling, it was Mr. Chater who encountered Mrs. Chater coming out of Lord Byron's room).
Jellaby delivers Lady Croom's tea and also a letter from Byron for Septimus, which Septimus burns to please Lady Croom, who is no longer a Byron fan.
Lady Croom asks if Septimus is going to follow the Chaters to the Indies, where Mr. Chater is playing botanist for an expedition led by Captain Brice, who has his own fixation on Mrs. Chater.
Septimus explains that it was only his unsatisfied desire for Lady Croom that led him to sleep with Mrs. Chater, a statement that Lady Croom takes as it was meant – as a compliment.
Lady Croom departs, telling Septimus to visit her in her sitting room at 7am – and to bring a book.